Hello Balint,
Please check whether the Auto-correct Afx window class names option is enabled in TestComplete. To do this, select Tools | Options from TestComplete main menu, then on the left side of the ensuing Options dialog, select Engines | General and find the option in the Object Naming group.
If the option is disabled, enable it and try to reproduce the issue. If the issue still persists, could you please use Contact Support web form to send us your project and your tested application (or a sample application that demonstrates the problem)? This will help us investigate the issue.
Thanks in advance.